Cleaning device and cleaning method

ABSTRACT

The invention relates to a cleaning device ( 10 ) and to a cleaning method performed using a cleaning device, in particular for cleaning, sterilizing or disinfecting dishes, working equipment, foodstuffs or the like, the cleaning device comprising a liquid cycle ( 11 ), wherein a cleaning liquid ( 17 ) can circulate in the liquid cycle, wherein items to be cleaned can be exposed to the cleaning liquid within the liquid cycle, the cleaning device comprising an electrolytic device ( 25 ) having a diamond electrode ( 28 ) for producing an oxidizing agent, the cleaning device having a feed line ( 21 ) that is connected to the liquid cycle, wherein the electrolytic device is connected to the feed line in such a manner that the oxidizing agent can be introduced into the liquid cycle via the feed line.

TECHNICAL FIELD

The invention relates to a cleaning device and to a cleaning methodperformed using a cleaning device, in particular for cleaning,sterilizing or disinfecting dishes, working equipment, foodstuffs or thelike, the cleaning device comprising a liquid cycle, wherein a cleaningliquid can circulate in the liquid cycle, wherein items to be cleanedcan be exposed to the cleaning liquid within the liquid cycle, thecleaning device comprising an electrolytic device having a diamondelectrode for producing an oxidizing agent, the cleaning device having afeed line that is connected to the liquid cycle.

BACKGROUND

Devices and methods of the aforementioned kind are sufficiently knownand are used and implemented in dish washers and similar cleaningdevices, for example. Moreover, they can also be used for cleaning ordisinfecting medical equipment, foodstuffs, such as fruits andvegetables, workpieces or the like. The known cleaning devices commonlycomprise a liquid cycle, in which a cleaning liquid is circulated withthe aid of a pump. In a section of the liquid cycle, the items to becleaned can be exposed to the cleaning liquid, for example by sprayingthe items with the cleaning liquid, so as to remove any pollutants thatmay be sticking to the item. The cleaning liquid is thus loaded withpollutants by repeatedly circulating in the liquid cycle. In particularin a dish washer these are mainly organic pollutants. Dish washers oralso other similar cleaning devices use tap water together with adetergent additive as a cleaning liquid, the items to be cleaned beingsprayed with the cleaning liquid until pollutants on a surface of theitems have been removed because of a mechanical and chemical removalprocess. Subsequently, the polluted cleaning liquid is pumped off,wherein the liquid cycle can be rinsed with tap water. The tap water orfresh water is fed into the liquid cycle via a feed line. After therinse, a cleaning process or cleaning cycle is usually complete. In acleaning process of this kind, a sterilizing or disinfecting effectsubstantially depends on the cleaning agents used and on thetemperatures of the liquids. The aim is to achieve a cleaning that is ascost-effective and environmentally friendly as possible through areduced use of cleaning agents and cleaning liquids or tap water.

From AT 502499 B1, a cleaning device and a method are known in which anelectrolytic device having a diamond electrode or an electrode pair isarranged in the liquid cycle. The cleaning liquid circulating in theliquid cycle flows past the electrodes, the diamond electrodes beingsupplied with electric current, which causes OH radicals to be producedin the cleaning liquid. Owing to their reactivity and oxidizing power,the OH radicals lead to an improved cleaning of the items with asimultaneously cytocidal effect on microorganisms and the like. Withregard to the structure and function of an electrolytic device of thiskind and its chemical cause-effect relationships, reference is made toAT 502499 B1.

The use of a diamond electrode is disadvantageous in that a lifespan ofthe diamond electrodes is substantially shortened if the diamondelectrodes come into contact with an acidic medium, such as acetic acidin a liquid cycle of a dish washer. Moreover, the removal of pollutantsfrom the items to be cleaned loads the cleaning liquid with undefinedsubstances, which may be electrochemically synthesized in theelectrolytic device. This can lead to the production of undesiredsubstances that could damage the items to be cleaned or the environment.Nevertheless, it is necessary for the diamond electrode to be in contactwith the cleaning liquid for as long as possible so as to produce alarge amount of the oxidizing agent.

Hence, it is the object of the present invention to propose a cleaningdevice and a cleaning method in which a lifespan of a diamond electrodeis prolonged.

SUMMARY

This object is attained by a device having the features of claim 1 andby a method having the features of claim 9.

The cleaning device according to the invention, in particular forcleaning, sterilizing or disinfecting dishes, working equipment,foodstuffs or the like, comprises a liquid cycle, wherein a cleaningliquid can circulate in the liquid cycle, wherein items to be cleanedcan be exposed to the cleaning liquid within the liquid cycle, thecleaning device comprising an electrolytic device having a diamondelectrode for producing an oxidizing agent, the cleaning devicecomprising a feed line that is connected to the liquid cycle, whereinthe electrolytic device is connected to the feed line in such a mannerthat the oxidizing agent can be introduced into the liquid cycle via thefeed line.

The cleaning liquid supplied to the cleaning device, i.e. to the liquidcycle, can preferably be continuously circulated within the liquidcycle. The cleaning liquid in the liquid cycle does not immediately comeinto contact with the electrolytic device, i.e. with the diamondelectrode, a contact of pollutants or acid components possibly presentin the cleaning liquid with the diamond electrode thus being avoided. Inthis manner, it is also possible to safely preclude a synthesis ofundesired substances due to electrolysis. Since the electrolytic deviceis connected to the feed line, the oxidizing agent produced by theelectrolytic device can also be supplied to the liquid cycle as freshwater via the feed line. At the beginning of a cleaning cycle, theliquid cycle is still being supplied or replenished with unpollutedcleaning liquid, wherein said cleaning liquid can be dosed with theoxidizing agent even prior to its introduction into the liquid cycle. Itis also possible to supply fresh cleaning liquid during a cleaning cyclevia the feed line, wherein said cleaning liquid can contain theoxidizing agent. It has proven unnecessary to subject a total amount ofcleaning liquid present in the liquid cycle to electrolytic treatment inorder to obtain a sufficient amount of oxidizing agent that is requiredfor a desired cleaning result. In fact, it is sufficient toelectrolytically treat or add oxidizing agent to only a part of thecleaning liquid present in the liquid cycle

Preferably, a circulator pump and a cleaning chamber for receiving andfor spraying items to be cleaned can be arranged in the liquid cycle.The cleaning device can then be integrated in a dish washer or the like,for example. In that case, the liquid cycle is a system that is closedoff from its environment. Independently thereof, however, the cleaningchamber can also be open towards its environment, for example in themanner of a chamber through which the items to be cleaned can becontinuously conveyed. With the aid of the circulator pump, it ispossible to spray the items to be cleaned with cleaning liquid and tosubsequently collect the cleaning liquid to use it repeatedly. Tap waterwith an added detergent or cleaning agent can be used as a cleaningliquid. The cleaning agent can then cause a removal of pollutants fromthe items to be cleaned due to a chemical removal process. In principle,the oxidizing agent can be added to the cleaning liquid at any pointduring a cleaning cycle. A large amount of tap water can be saved inparticular by the repeated use of the cleaning liquid and itscirculation in the liquid cycle.

It is particularly advantageous if an admixing device of the cleaningdevice is arranged in the liquid cycle, wherein the oxidizing agent canthen be admixed to the cleaning liquid present in the liquid cycle viathe admixing device. In this regard, it is immaterial whether thecleaning liquid present in the liquid cycle already contains anoxidizing agent. A desired cleaning result can be achieved even at asmall amount of oxidizing agent in the liquid cycle. However, theoxidizing agent can be consumed by a reaction with other substancesduring circulation in the liquid cycle so that it may be useful tomaintain a concentration of the oxidizing agent by admixing.Furthermore, the admixing device can have a check valve that makes surethat polluted cleaning agent cannot flow from the liquid cycle into thefeed line. In this manner, it can be ensured that only unpollutedcleaning agent or also fresh water can enter the liquid cycle via thefeed line.

The admixing device can comprise a jet pump within the liquid cycle.Since a circulation of the cleaning liquid in the liquid cycle forms aflow anyway in the liquid cycle, which is formed by liquid conduits atleast in sections, cleaning liquid can be suctioned from the feed lineby means of the jet pump and be admixed to the liquid cycle. The jetpump can be realized in the manner of a water jet pump that causes aparticularly thorough mixing of the cleaning liquid present in theliquid cycle and the freshly added cleaning liquid from the feed line.Besides, the use of a jet pump can also promote a reaction of theoxidizing agent with substances or pollutants present in the cleaningliquid.

In one embodiment, the admixing device can comprise a buffer tank in thefeed line. The buffer tank can contain fresh cleaning liquid that isloaded with the oxidizing agent. The fresh cleaning liquid can then becontinuously added to the cleaning liquid present in the liquid cycle oralso at intervals, i.e. at certain points of the cleaning cycle. The useof a buffer tank or of a buffer reservoir allows the electrolytic deviceto be operated continuously and setting a desired concentration of theoxidizing agent in the later added fresh cleaning liquid. Cleaningliquid including an oxidizing agent can also be stored in the buffertank so that after a cleaning cycle, fresh unpolluted cleaning liquidwith the oxidizing agent is available for a subsequent cleaning cyclewithout first having to be produced in a drawn-out electrolytic process.

The cleaning device can also have a dosing device for an electrolyte,wherein the dosing device can be connected to the electrolytic deviceand/or to the feed line in such a manner that the electrolyte can beintroduced into the electrolytic device. The electrolyte can inparticular be a salt that serves as a cation source for electrolysis andis mixed with tap water that is supplied via the feed line. The dosingdevice can dose the salt as required directly into the feed line or,initially independently of the feed line, provide brine that is thendosed into the feed line. Alternatively, the dosing device can dose thesalt or the brine directly into the electrolytic device. For handlingthe brine, the dosing device can have a mixing chamber and, if needed, abuffer reservoir.

It is particularly advantageous if the electrolytic device is arrangedin a shared housing with the admixing device, the circulator pump and/orthe dosing device, wherein the housing can then be connected to theliquid cycle. For example, the housing can be made of aninjection-molded plastic material or also of another suitable material.The liquid cycle can then be guided directly through the housing,wherein the feed line can then also be connected to the housing. Inparticular if the electrolytic device is arranged in the housingtogether with another structural component of the cleaning device, suchas the admixing device, the circulator pump and/or the dosing device,maintenance and repair as well as assembly of the cleaning device issignificantly simplified. In case of a defect of one of the structuralcomponents, the housing then has to simply be separated from the liquidcycle and from the feed line and be replaced if needed. Also, sharedcontrol devices for the aforementioned structural components can then bearranged in the housing, which can then also have a shared power supply.

For an anode or cathode, the electrolytic device can have a diamondelectrode and/or a pyrolytically coated graphite electrode and/or astainless steel electrode. Thus, a pair of diamond electrodes can beprovided, wherein a diamond electrode can also be combined with apyrolytically coated graphite electrode. By using the pyrolyticallycoated graphite electrode, an even further prolonged lifespan of theelectrolytic device and of the electrode can be achieved. Furthermore,in case of a defect of the diamond electrode or of the graphiteelectrode, only carbon comes into contact with the items to be cleaned.

The afore-described cleaning device can be integrated into a dishwasher.

The cleaning method according to the invention is implemented using acleaning device, in particular for cleaning, sterilizing or disinfectingdishes, working equipment, foodstuffs or the like, a cleaning liquidbeing circulated in a liquid cycle of the cleaning device, wherein itemsto be cleaned can be exposed to the cleaning liquid within the liquidcycle, an oxidizing agent being produced by means of an electrolyticdevice having a diamond electrode of the cleaning device, the cleaningdevice having a feed line that is connected to the liquid cycle, whereinthe electrolytic device is connected to the feed line, the oxidizingagent being introduced into the liquid cycle via the feed line. Withregard to the advantageous effects related to the method according tothe invention, reference is made to the description of the advantages ofthe device according to the invention.

The oxidizing agent can be admixed to the cleaning liquid in the liquidcycle.

Furthermore, the electrolytic device can be supplied with fresh water ortap water and/or brine. Thus, the electrolytic device does not have tobe arranged directly in the feed line. Instead, the electrolytic devicecan also be arranged in such a manner that the oxidizing agent producedby means of the electrolytic device is introduced into the feed line. Ifthe electrolytic device is arranged directly at the feed line, theelectrolytic device can be rinsed with the fresh water because then saidfresh water can flow through the electrolytic device.

Furthermore, it may be provided that electric current is conducted viathe diamond electrode only towards the end of a cleaning cycle. In thiscontext, a cleaning cycle is a period of time that is required for acomplete cleaning of the items to be cleaned. The cleaning cycle cancomprise multiple cleaning steps at a repeated change of cleaningliquids. If required, it may also be provided that the oxidizing agentis produced towards the end of the cleaning cycle by supplying electriccurrent to the diamond electrode, i.e. to the electrolytic device. Sincesterilization or disinfection of the items to be cleaned can be achievedwith the oxidizing agent, this sterilization or disinfection can beadvantageously performed in the last cleaning step once the substantialpollutions have been removed from the item. For instance, tap water thatis used for rinsing the liquid cycle of the items to be cleaned can beloaded with the oxidizing agent.

Furthermore, it may be provided that ozone is produced by means of theelectrolytic device. Ozone (O₃) is a relatively strong oxidizing agent,which can also irritate the airways in humans. If the ozone is added ina dosed manner in a closed liquid cycle and if it is largely depletedduring a cleaning cycle, however, an adverse effect of this kind can beavoided while particularly good cleaning results can be achieved. Also,in this case, an additional loading of fresh water with NaCl isunnecessary.

It may also be provided that free chlorine or chlorine oxide is producedby means of the electrolytic device. This can take place in addition tothe production of ozone or as an individual process. The free chlorineor chlorine oxide can be produced in the form of hypochlorous acid as anoxidizing agent. In particular if fresh water is loaded with NaCl, NaClOcan be produced from a solution of this kind. By means of acorresponding control of the electrolytic device, the production ofozone can also be prevented if doing so is advantageous.

In a sump of the liquid cycle, cleaning liquid can be stored for acleaning cycle that follows after an undefined period of time. The sumpcan be arranged within or below a cleaning chamber for collectingresidual cleaning liquid in the cleaning cycle. To save cleaning liquidand fresh water, it may be provided in the cleaning method that not allthe cleaning liquid in the liquid cycle, which is possibly spent, ispumped off and disposed of after the last cleaning step of a cleaningcycle. This is a regular process in dish washers, for example, so as toavoid that potential pollutants, such as food scraps, remain in the sumpfor a longer period of time. Under certain circumstances, this mightlead to an undesired unpleasant smell. If the cleaning liquid is nowloaded with an oxidizing agent, the cleaning liquid located in theliquid cycle can be successfully sterilized. The cleaning liquid that ispresent in the liquid cycle after the last cleaning step can then be atleast partially stored or saved in the sump for a cleaning cycle thatfollows after an undefined period of time. Then, it is no longernecessary to use fresh water in particular for a pre-cleaning of itemsto be cleaned, which may allow saving an enormous amount of water.

Advantageous embodiments of the method become apparent from thedependent claims back-referenced to device claim 1.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

In the following description, the invention is explained in more detailwith reference to the accompanying drawings.

In the figures:

FIG. 1 shows a schematic illustration of a first embodiment of acleaning device;

FIG. 2 shows a schematic illustration of a second embodiment of acleaning device;

FIG. 3 shows a schematic illustration of a third embodiment of acleaning device.

DETAILED DESCRIPTION

FIG. 1 shows a schematically illustrated cleaning device 10 that isintegrated in a so-called dish washer (not illustrated). The cleaningdevice 10 substantially comprises a liquid cycle 11 that is formed byconduit sections 12, 13 and 14 and by a cleaning chamber 15. In theliquid cycle 11, a circulator pump 16 is further integrated so that thecleaning liquid 17, which can be collected in a sump 18 of the cleaningchamber 15, can be pumped through the conduit sections 12, 13 and 14 bythe circulator pump 16 and be sprayed via nozzles 19 into an interior 21of the cleaning chamber 15 and onto items to be cleaned (notillustrated). The circulator pump 16 can also be replaced with a jetpump (not illustrated). The items to be cleaned can be dishes, workingequipment, workpieces or similar objects that are suitable for beingcleaned in a dish washer.

The cleaning device 10 further comprises a feed line 21 that is formedby conduit sections 22, 23 and 24 and is connected to a fresh watersupply or to a tap water connection (not illustrated). An electrolyticdevice 25 of the cleaning device 10 is connected to the feed line 21.The electrolytic device 25 is integrated or arranged in particularbetween conduit sections 22 and 23 in the feed line 21. The electrolyticdevice 25 is substantially composed of an electrode chamber 26 and anelectrode pair 27 of diamond electrodes 28 and a power supply connection29 for the diamond electrodes 28. Tap water (not illustrated) can flowthrough the electrode chamber 26 comprising the diamond electrodes 28.

Furthermore, a dosing device 30 of the cleaning device 10 is provided,said dosing device 31 being connected to conduit sections 23 and 24 viaa conduit section 31. The dosing device 30 has a dosing tank 32 in whicha salt or brine (not illustrated) can be stored. With conduit section31, a valve 33 is arranged via which the salt or the brine can beadmixed as an electrolyte to the tap water flowing in from conduitsection 24. A fresh water supply can be controlled in a mechanizedmanner via a valve 34 in conduit section 24.

By means of the electrolytic device 25, an oxidizing agent, such asozone, can now be generated from the tap water loaded with theelectrolyte in the electrode chamber 26 by means of the diamondelectrodes 28. In conduit section 22, a valve 35 is arranged via whichthe tap water with the oxidizing agent can be introduced in a dosedmanner into the liquid cycle 11. Conduit section 22 ends in the liquidcycle 11 between conduit section 13 and 14 in such a manner that the tapwater with the oxidizing agent can be admixed to the cleaning liquid 17in the liquid cycle 11 without allowing the cleaning liquid 17 to flowinto the feed line 21. In this manner, a contact between the diamondelectrodes 28 and the cleaning liquid 17 from the liquid cycle 11, whichmay oftentimes carry pollutants, is effectively prevented.

FIG. 2 shows a schematic illustration of a cleaning device 36, saidcleaning device 36 having the liquid cycle 11 previously described inFIG. 1. Again, an electrolytic device 38 is arranged in a feed line 37.The feed line 37 comprises conduit sections 39, 40 and 41, theelectrolytic device 38 being arranged between conduit sections 39 and40, fresh water thus being able to flow through it. Between conduitsections 40 and 41, another conduit section 42 branches off, which isconnected to a mixing chamber 43 of a dosing device 44. Moreover, themixing chamber 43 is connected to the electrolytic device 38, moreprecisely to its electrode chamber 46, via a conduit section 45. Themixing chamber 43 is supplied with salt or brine via a dosing tank 47and a conduit section 48. Fresh water can be supplied in a dosed mannerto the mixing chamber 43 via a valve 49 in conduit section 41, wherein,after a desired degree of saturation or mixing ratio has been reached inthe mixing chamber 43, the thus prepared electrolyte solution can beintroduced as needed into the electrode chamber 46 via another valve 50in conduit section 45. Furthermore, a valve 51 for controlling a freshwater supply to the electrode chamber 46 is provided in conduit section40 and a valve 52 for dosed discharge of the oxidizing agent generatedby means of the electrolyte device 38 into the liquid cycle 11 isprovided in conduit section 39.

FIG. 3 shows a schematic illustration of a cleaning device 53 having aliquid cycle 54 in which a jet pump 55 is arranged other than in theliquid cycle shown in FIGS. 1 and 2. In a feed line 56, whichsubstantially corresponds to the feed line described in FIG. 2, a bufferreservoir 58 and successively a check valve 59 are arranged between thevalve 52 and the jet pump 55 in a conduit section 57. The check valve 59prevents polluted cleaning liquid 17 from flowing out of the liquidcycle 54 into conduit section 57 or into the buffer reservoir 58. In thebuffer reservoir 58, tap water loaded with oxidizing agent can be storedso that during operation of the jet pump 55 and during circulation ofcleaning liquid 17 in the liquid cycle 54, liquid can be continuouslytapped from the buffer reservoir 58 and be admixed to the cleaningliquid 17 located in the liquid cycle 54 via the jet pump 55.

1. A cleaning device (10, 36, 53), in particular for cleaning,sterilizing or disinfecting items, the cleaning device comprising aliquid cycle (11, 54), wherein a cleaning liquid (17) can circulate inthe liquid cycle, wherein items to be cleaned can be exposed to thecleaning liquid within the liquid cycle, the cleaning device comprisingan electrolytic device (25, 38) having a diamond electrode (28) forproducing an oxidizing agent, the cleaning device having a feed line(21, 37, 56) that is connected to the liquid cycle, characterized inthat the electrolytic device is connected to the feed line in such amanner that the oxidizing agent can be introduced into the liquid cyclevia the feed line.
 2. The cleaning device according to claim 1,characterized in that a circulator pump (16) and a cleaning chamber (15)for receiving and for spraying the items to be cleaned with cleaningliquid (17) are arranged in the liquid cycle (11, 54).
 3. The cleaningdevice according to claim 1, characterized in that an admixing device ofthe cleaning device is arranged in the liquid cycle (11, 54), whereinthe oxidizing agent can be admixed to the cleaning liquid (17) in theliquid cycle via the admixing device.
 4. The cleaning device accordingto claim 3, characterized in that the admixing device comprises a jetpump (55) within the liquid cycle (54).
 5. The cleaning device accordingto claim 3, characterized in that the admixing device comprises a buffertank (58).
 6. The cleaning device according to claim 1, characterized inthat the cleaning device (10, 36, 53) has a dosing device (30, 44) foran electrolyte, the dosing device being connected to the electrolyticdevice (25, 38) and/or to the feed line (21, 37, 56) in such a mannerthat the electrolyte can be introduced into the electrolytic device. 7.The cleaning device according to claim 2, characterized in that theelectrolytic device (25, 38) is arranged in a shared housing with theadmixing device, the circulator pump (16) and/or the dosing device (30,44), the housing being connected to the liquid cycle (11, 54).
 8. Thecleaning device according to claim 1, characterized in that for an anodeor cathode, the electrolytic device (25, 38) has a diamond electrode(28) and/or a pyrolytically coated graphite electrode and/or a stainlesssteel electrode.
 9. A cleaning method, performed using a cleaning device(10, 36, 53), in particular for cleaning, sterilizing or disinfectingitems, a cleaning liquid (17) being circulated in a liquid cycle (11,54) of the cleaning device, wherein items to be cleaned can be exposedto the cleaning liquid within the liquid cycle, an oxidizing agent beingproduced by means of an electrolytic device (25, 38) having a diamondelectrode (28) of the cleaning device, the cleaning device having a feedline (21, 37, 56) that is connected to the liquid cycle, characterizedin that the electrolytic device is connected to the feed line, theoxidizing agent being introduced into the liquid cycle via the feedline.
 10. The cleaning method according to claim 9, characterized inthat the oxidizing agent is admixed to the cleaning liquid (17) in theliquid cycle (11, 54).
 11. The cleaning method according to claim 9,characterized in that the electrolytic device (25, 38) is supplied withfresh water.
 12. The cleaning method according to claim 9, characterizedin that electric current is conducted via the diamond electrode (28) atdefined intervals.
 13. The cleaning method according to claim 9,characterized in that electric current is conducted via the diamondelectrode (28) only towards the end of a cleaning cycle.
 14. Thecleaning method according to claim 9, characterized in that ozone isproduced by means of the electrolytic device (25, 38).
 15. The cleaningmethod according to claim 9, characterized in that free chlorine isproduced by means of the electrolytic device (25, 38).
 16. The cleaningmethod according to claim 9, characterized in that cleaning liquid (17)is stored in a sump (18) of the liquid cycle (11, 54) for a cleaningcycle that follows after an undefined period of time.